Creating a 3D Print From Maya
There are two important things to remember when preparing a 3D Print.
1. The model must be ‘watertight.’ This means that the object to be printed must be a solid surface with a thickness, and it cannot have any holes in it. If you were to fill it with water, none would leak out.
2. All surface Normals must be facing the same direction.
The Z Corp 3D Printers recognize Stereolithography (.stl) files. Maya does not export .stl files so we will use either Rhino or 3DS Max. I will explain how to use both.
Step 1: Export .obj from Maya
By default Maya does not load the OBJ exporter. To do this go to Windows –> Settings/Preferences –> Plug-in Manager.
Note: Do not check auto-load for all the plug-ins at random. This causes problems for Maya. Only load the Plug-Ins you know you are going to use.
Once you have loaded the OBJ Exporter then click ‘Refresh’ and then ‘Close.’
Now select the object you want to export. Go to File –> Export Selection and open the dialog box.
Printing from RHINO:
Open Rhino. First type ‘Options’ into the Command Line. Hit enter.
Open the pulldown menu next to Backface Settings, select ‘Single Color for All Backfaces.’
Changing Backfaces to green will make all ‘Inverted Normals’ appear green, so you know something is wrong. All normal faces will be the correct object color.
An object with an inverted normal will now look like this:
To fix this first explode the object (type ‘explode’ into the command line) or ungroup (type ‘ungroup’ ) until you are able to select individual faces. Select the inverted face and type ‘flip’ into the command line. The face is no longer green.
Select all faces in the object. Type ‘join’ into the command line. You now have a single object with all the normals facing the correct direction.
Now on to the 3D Print.
Type ‘Import’ into the dialog box. Navigate to your OBJ file and select open.
If your model appears slightly different from the model in Maya, as mine does above, select your model and type in Explode.
The fact that everything is green is good. This means all our faces are facing the same direction, but they are facing the wrong direction.
To fix this Select the entire object and type ‘flip.’ as shown above.
Select the entire object again and type ‘join,’ again as shown above.
Your model should now look as it did in Maya. Orbit around make sure there are no other Normal issues. In this case we are good to go!
Scaling the Object for Printing.
If you are printing to a specific scale you must first take your object by the appropriate scale factor. 1/96 for 1/8″=1′-0″, or 1/48 for 1/4″=1′-0″ for example.
Since we are dealing with an abstract object we do not need a precise scale. We do need to scale the object to a size appropriate for the 3D printer.
The Printer Bed is 8″*10″*10″
Create a Box with these dimensions.
Only one more step. We have to make sure the object is water tight.
For this we will use the ‘OffsetMesh’ command.
Delete the box, we don’t need it anymore. Select your model and type ‘offsetMesh’ into the Command Line.
Now In order to be structurally sound a 3D print needs to be at least 1/8″ thick. Since our model from Maya already has thickness however, so in this case we only need to add a nominal thickness to make sure all the surface intersections are closed.
Check the box ‘Delete Input Mesh’ use a thickness of .02 and select ‘OK.’ Make sure the offset did not create any Normals. Ours did not.
We are now ready to export to Z Print.
Select your model, type ‘export’ into the Command Line.
Printing from 3DS MAX:
Open 3DS Max
As with Rhino I will again first explain how to solve Normal Issues. Max is prepared to show flipped Normals without any extra set up by us. Thank you 3DS Max!
Objects without inverted Normals show as the object color. Inverted Normals appear black, instead of object color.
To fix this open the Modify panel, select edit ‘polygon.’ ‘Polygon’ is 3DS Max’s word for ‘FACE’. Now select the inverted (black) polygon. Then on the Modify Panel click ‘Flip.’
Now, onto our Model. Click on the Max Logo –> Import –> Import
Select the OBJ file we exported from Maya. Click ‘OK.’
(Note: If your model shows up with the object color, and not black with a colored wireframe, skip ahead to scaling the object.)
As in the Rhino example all of our Normals are inverted. Open the Modify Panel, as above. Select ‘Polygon’ Select the entire model. Click ‘Flip.’
Scaling the Model for Printing.
Again we will scale our geometry to fit with a 8″x10″x10″ box, the size of the printer bed.
First a note about scale factors in Max. You cannot simply type in the scale factor as you can in Rhino. It is slightly more complicated.
To scale to a scale factor you must first determine that scale factor as a percentage. Max does not use fractions.
To scale to 1/8″=1′-0″ for example, we must first find out scale factor. We know it is 1/96 or .010416666666667. As a percentage this is 1.0416666666667
Now, Select the object you wish to scale.
First click and hold on the Scale Tool and select ‘Uniform Scale.’
Then click and hold on the Selection Model and select ‘Use Selection Center.’
Type in your scale percentage and hit Enter.
For abstract scaling create a box that is 8″x10″x10″
Scale your model down until it fits inside the box.
Now we must make sure the model is water tight for printing.
Delete the box. We don’t need it anymore.
Even though we visually scaled down the model, 3D Max still retains its original site. If you right click on the model and open the Object Properties you will see that its dimensions are still greater than 8″x10″x10″.
To fix this select your Object. Open the Utilities panel (The Hammer Icon). Click ‘Reset X-Form’ then click ‘Reset Selected.’
Now right click on your Object, and select Convert to –> Editable Poly. This deletes the object history.
Select the geometry, open the modify panel. Click on the Modifier pulldown and select ‘Shell.’
Since we did the reset x-form however, we can work at fractions and add a shell of the appropriate size. As this model already had a certain thickness from Maya, we only need to at a nominal shell to print correctly. Instead of 1/8″ we can use 1/16″ for this particular model.
Type 1/16″ into the outer shell window.
Now once again check for Normals. We are ok, so right click and convert to Editable Poly one more time, and we are ready to export.
Select the Object first, then navigate to the Max Logo –> Export –> Export. DO NOT USE THE EXPORT SELECTED OPTION IT WILL NOT WORK FOR 3D PRINTING!!!
Congratulations! You have successfully exported your STL file.
Now for the last step.
Open Z Print.
When prompted open your .stl file.
You should see something like this:
Excellent. Now we check for Normals. Go to Edit –> Normals –> Invert All Normals
Now you should see something like this:
Just like in Rhino and Max we have turned all of the faces inside out and now they are black. This is good. If you look closely at the above image you will see a handful of small white dots. These are improperly aligned Normals.
However, if all you see are tiny dots like this your Model has been successful. If you see larger white areas then you will have print problems and it will be necessary to repeat the export process until there are no large areas of white.
But, this model is ready to go. Go back to Edit –> Normals –> Invert All Normals to make the model right side out again.
The last thing we do is go to View –> Calculate Part Statistics
WHOA!! That’s crazy, right? Maybe. If the cost is very high you can go back to Rhino or Max and rescale the object to make it smaller.
But be sure not to make it too small.
Guess what?! You’re Done. If you have successfully created a .stl file with no Normal issues its time to truck on over to the 3D print lab and make this dream a reality!